1. Field of the Invention
The present invention is directed to a fitting adapted to be used to inject sealant into the packing of a pressurized fluid member so as to eliminate or substantially reduce leakage therethrough. More particularly, the present invention relates to a fitting adapted to be friction welded to a pressurized valve or pressure containing component, and a method for connecting said fitting.
2. Description of the Prior Art
The chemical, petroleum, petrochemical, and other heavy industries are often organized in large industrial complexes for the purposes of refining and/or processing a variety of gaseous and liquid products. Due to the nature of these products, such complexes are often characterized by the presence of many miles of conduit and piping which serve to convey such products throughout the industrial complex. The products carried by these pressurized pipelines may be highly corrosive, caustic, or toxic in nature. Alternatively, such products may be flammable or explosive, or otherwise hazardous should they be released into the environment.
Notwithstanding the environmental impact and other hazards which might result from the open, uncontrolled release of many of these chemicals, low grade releases or "leaks" are nevertheless fairly commonplace. Such releases often occur as a result of the failure of valving which is necessarily integrated into the aforedescribed pipeline network. Such failures usually occur when the valve packing deteriorates so as to allow fluid flow along the valve stem. Alternatively, failure occurs when the packing is compressed to the limits of the packing gland follower. Other leakages can be caused by seared or damaged valve seats which also allow leakage from the pressurized fluid member.
It is often possible to reduce or eliminate such packing failure by injecting a sealant into the packing cavity or valve seat area. Sealant may also be injected into valve or pipe clamps to reduce or substantially eliminate leakage along the seams of the clamp. The economics of the industrial complex, however, dictate that such repair measures be ordinarily carried out while the valve remains situated in a fully pressurized, operable line. As a result of such working environments, sealant injection into the valve must be carried out in a fashion so as to reduce the exposure to the technician as well as to prevent further and perhaps explosive leakage of possibly hazardous or toxic chemicals.
A number of techniques have thus been developed to enable sealant to be injected into a pressurized valve. One such technique involves the threaded attachment of a fitting to the exterior of the valve housing. In this technique, the attachment of such a fitting is accomplished by first drilling a pilot hole partway into the valve. This pilot hole is then threaded in a manner to accommodate the insertion of the threaded connector. Once the connector is secured to the valve housing, the hole in the valve housing is completed so as to allow the injection of sealant into the valve packing.
Disadvantages of such techniques include the possibility that the pilot hole will be accidentally completed through the pressure boundary of the valve. In the event of an accidental penetration of the valve housing, fluid carried by the valve is uncontrollably released through the pilot hole and into the environment. When this material is superheated, corrosive, or poisonous, even temporary exposure may result in a life threatening situation, both to the person attempting to complete the fitting, as well as to persons in the immediate area of valve itself. Further disadvantages with this technique include the creation of a connection which is considerably weaker than the original valve housing. In this connection, a weakened area is created in the valve housing which must be replaced at the earliest opportunity. Because of the restricted and temporary nature of such fittings, as well as the effort involved in their creation, such techniques are therefore relatively expensive.
As a result of the above disadvantages, other techniques and apparatus have been developed to inject sealant into a pressurized valve. One alternate technique involves the welding of a fitting to the exterior of the valve housing. Once the fitting has been welded to the exterior of the valve, a hole is then completed through the fitting into the valve packing whereupon sealant may then be introduced. Disadvantages, however, also exist with this technique. Such disadvantages include the inherent danger of using an open flame in areas where leakage is known to be present. If such leakage involves a flammable gas or liquid, a significant danger of fire or explosion is presented. Conventional welding also offers the potential for weakening of the pressure boundary of the valve due to metal thickness variations and the high heat necessarily generated during the normal weld process. Conventional welding techniques also create the possibility of hydrogen embrittlement, weld dilution, weld inclusion, and stress corrosion cracking. Furthermore, the time involved in the creation of a conventional weld may be significantly increased if surface preparation is required.
Further disadvantages of the traditional welded fitting include its restricted use to materials that do not decompose upon the addition of heat. Even where a flammable material is not directly introduced into the area surrounding the valve, a dangerous situation can nevertheless be presented if the valve controls the flow of materials such as acetylene, ethylene, or butadiene which do not require the presence of oxygen for flammable combustion, and may therefore decompose violently merely upon the addition of heat. Further, fittings welded with conventional techniques also result in the production of a weak area which must be removed and replaced at the earliest opportunity. Such techniques are therefore also relatively expensive in nature.